Cutaneous colonization by Staphylococcus aureus in infancy plays an active role in the development of atopic dermatitis (AD), according to the results of a prospective birth cohort study published in the Journal of Investigative Dermatology.
The study enrolled 149 white infants with and without a family history of atopy between July 2010 and November 2012. Study participants were divided into 2 groups: high-risk (infants with ≥1 first-degree relative with atopy) and low-risk (infants with no family history of atopy). Culture-based analysis was performed via axillary and antecubital fossa skin swabs collected at birth and at 7 time points over the infants’ first 2 years of life.
Of the 149 children assessed, 36 developed AD at a mean age of 9.4 months (range,
10 to 24 months), with a mean SCORAD (SCORing Atopic Dermatitis) index of 20.1 (range, 8.0-35.5). In 56% (20 of 36) of the infants who developed AD, the disease presentation was prior to 6 months of age.
Cumulative AD incidence during the first 2 years of life was 2.6 times as high in the high-risk vs low-risk arms (31% vs 12%, respectively), with the disease presenting more often in winter than in summer (36% vs 14%, respectively). Although AD risk was about 1.7 times as high in boys as in girls, no association was observed between season of birth and AD risk.
At 3 months of age, S aureus was more prevalent on the skin of infants who developed AD later in life. Compared with age-matched controls, the prevalence of AD was increased on the skin of infants at the time of AD onset, as well as at 2 months prior to disease onset. In addition, at the onset of AD, infants who tested positive for S aureus were younger than their uncolonized counterparts.
The researchers concluded that specific changes in early-life skin colonization by S aureus may contribute to the development of AD in infancy.
Meylan P, Lang C, Mermoud S, et al. Skin colonization by Staphylococcus aureus precedes the clinical diagnosis of atopic dermatitis in infancy [published online August 22, 2017]. J Invest Dermatol. doi: 10.1016/j.jid.2017.07.834